MLA

Butts, Mary, 1890-1937. Auric, Georges. Box 1, folder 9. n.d.. https://collections.library.yale.edu/catalog/16893636.

APA, 6th edition

Butts, Mary, 1890-1937. (["Box 1, folder 9"])(n.d.)[Auric, Georges]. https://collections.library.yale.edu/catalog/16893636.